1. Field of the Invention
The present invention relates to a semiconductor memory device. More particularly, it relates to a semiconductor memory device enabling a multi-direction data selection, especially a two or more direction data read and/or write in a logical bit map space.
2. Description of the Related Art
In an image data processing system, for example, in a computer tomography (CT) scanning system, three dimensional bit map data are used and each data has a color and gradation indicating density. In the CT scanning system or the like, a high-speed reading of a plurality of data in a X-, Y- or plane-direction of a three dimension bit map space is required.
Conventional memory devices are essentially accessed in only one direction, for example, by a word line and bit lines. However, the conventional memory devices cannot. achieve a multidirection access, in other words, a high dimension access, because, for example, in a two dimension logical bit map space, a plurality of bit data in a X direction can be read by one access, but a plurality of accesses for reading a plurality of bit data in a Y direction is required.